Solderable contacts are used, for example, for SMD components (surface mounted components) or for components mounted in a flip-chip arrangement. In the flip-chip arrangement, a chip having component structures on its surface is soldered using bumps made of solder on a carrier substrate. This has the advantage that the expense for contacting is low, that, apart from the space required for the chip on the carrier substrate, no additional surface is required for the contacting, and that the component structures are protected by the arrangement between the chip and the carrier substrate.
SAW components, which can be used, for example, as filters in cell phones, are subject, as are cell phones, to an ever-increasing demand for miniaturization. With the help of a flip-chip arrangement, SAW components can be encapsulated in a simple way by CSS plus technology developed by the applicant, in such a way that the chip size in practice determines the component size directly, and thus the CSSP package (chip sized SAW package) is produced. A possible example of such a CSS plus packaging is provided, for example, from WO03/058812.
As a result of the increasing miniaturization, it is necessary to save as much space as possible on the chip surface and to reduce the surface area of all the component structures on the surface. This has the consequence that, for example, the solderable contacts as well, and the under bump metallizations (UBM) have to become smaller. In modern components for the 9 GHz range, the UBMs have, for example, only a diameter of approximately 90 μm. However, it has been found that with these small bump diameters, the mechanical stability of the soldering sites suffers, and there is an increased risk that the soldering sites will tear loose, and thus that the component will be damaged.